Silicone everywhere for me, it won't look out of place provided the colour is right and it's done neatly. I would question why wouldn't you seal between the floor and the walls/pan on a floor that's likely to get wet.
But you've got a loft leg every 600mm in every direction - correct?
TBH if I was forced to use loft legs I would probably have a bit of timber around the perimeter of the boarded space but that's because I think having the boards unsupported around the edges is a bit crap. But then I would...
Looks fairly standard of the stuff that you get delivered, rough with the smooth and all that. Unless you take the time to go and sort out which bits of timber you want from the supplier. Maybe next time upload even more photos.
Normally , or at least in the past (20 years or so), there would be a coax cable fitted from the living area up to the loft, then the new owner is expected to fit an aerial.
It will be heavy so might be helpful to have an assistant. But have you actually checked if taking the door off will be enough? How would taking the handle off help? Surely the pinch point is when then door is open - the gap between the open door on the left and frame on the right?
AFAIK you need to pop that cap off (1.47), then undo the four screws (2.29) for each hinge.
Unless @crank39 or @ronniecabers know of an easier/better way.